\section{Group -- Hybrid Model}\label{group-hybrid-model}

\subsection{HybridModel:Zone}\label{inputs-hm}

This object provides a hybrid model feature to enhance energy simulations for existing buildings by inversely solving hard-to-measure model input parameters. More specifically, zone internal thermal mass, air infiltration rate (ACH), and people count are usually hard to be measured directly yet important in building energy simulations. The hybrid model takes measured zone air temperature, humidity ratio, or CO$_2$ concentration as inputs and inversely solve those unknown parameters based on the zone air heat, moisture, or CO$_2$ balance algorithms. The inversely solved internal thermal mass, air infiltration rate, and people count can then be used to substitute the original simplified assumptions to enhance the energy simulation.

\subsubsection{Inputs}\label{inputs-hybridzone}

\paragraph{Field: Name}\label{field-name-hm}

The name of the HybridModel:Zone object.

\paragraph{Field: Zone Name}\label{field-zone-name-hm}

This field is the name of the thermal zone (ref: Zone) and attaches a particular hybrid model input to a thermal zone in the building.

\paragraph{Field: Calculate Zone Internal Thermal Mass}\label{field-calculate-zone-internal-thermal-mass-hm}

This field is used to provide an option to calculate the temperature capacity multiplier required by \hyperref[zonecapacitancemultiplierresearchspecial]{ZoneCapacitanceMultiplier:ResearchSpecial}. The temperature capacity multiplier is represented as internal thermal mass multiplier in the hybrid model. When YES is selected, the hybrid model calculates the multiplier based on the inverse heat balance algorithm using the measured zone air temperature.

Output for this parameter can be found via the output variable listed below.  Additionally, an average for the simulation is also provided in the table report \hyperref[input-verification-and-results-summary-or-ivrs]{Input Verification and Results Summary} subtable \textit{Hybrid Model: Internal Thermal Mass}.

\paragraph{Field: Calculate Zone Air Infiltration Rate}\label{field-calculate-zone-air-infiltration-rate-hm}

This field is used to provide an option to calculate the zone air infiltration rate - air change per hour (ACH).
When YES is selected, the hybrid model calculates the zone air infiltration rate based on one of the following balance equations: 1. Heat balance equations, 2. Moisture balance equations, 3. CO$_2$ balance equations when the corresponding data requirements are met. The HybridModel will be activated with the following options:

1. When Zone Measured Air Temperature Schedule Name is provided, it will calculate the zone air infiltration rate assuming the HVAC system is free-floating using the zone sensible heat balance algorithms;

2. When Zone Measured Air Temperature Schedule Name, Zone Input Supply Air Mass Flow Rate Schedule Name, and Zone Input Supply Air Temperature Schedule Name are provided, it will calculate the zone air infiltration rate assuming the HVAC is on. In this case, the zone air supply air temperature and mass flow rate in the zone sensible heat balance algorithms will be overwritten by the input data;

3. When Zone Measured Air Humidity Ratio Schedule Name is provided, it will calculate the zone air infiltration rate assuming the HVAC system is free-floating using the zone moisture balance algorithms;

4. When Zone Measured Air Humidity Ratio Schedule Name, Zone Input Supply Air Mass Flow Rate Schedule Name, and Zone Input Supply Air Humidity Ratio Schedule Name are provided, it will calculate the zone air infiltration rate assuming the HVAC is on. In this case, the zone air supply air humidity ratio and mass flow rate in the zone moisture balance algorithms will be overwritten by the input data;

5. When Zone Measured Air CO$_2$ concentration Schedule Name is provided, it will calculate the zone air infiltration rate assuming the HVAC system is free-floating using the zone CO$_2$ balance algorithms;

6. When Zone Measured Air CO$_2$ concentration Schedule Name, Zone Input Supply Air Mass Flow Rate Schedule Name, and Zone Input Supply Air CO$_2$ Concentration Schedule Name are provided, it will calculate the zone air infiltration rate assuming the HVAC is on. In this case, the zone air supply air CO$_2$ concentration and mass flow rate in the zone CO$_2$ balance algorithms will be overwritten by the input data;

When YES is selected for Calculate Zone Internal Thermal Mass, this field will be treated as NO.

\paragraph{Field: Calculate Zone People Count}\label{field-calculate-zone-people-count-rate-hm}

This field is used to provide an option to calculate the zone people count.
When YES is selected, the hybrid model calculates the zone people count based on one of the following balance equations: 1. heat balance equations, 2. Moisture balance equations, 3. CO$_2$ balance equations when the corresponding data requirements are met. The HybridModel will be activated with the following options:

1. When Zone Measured Air Temperature Schedule Name is provided, it will calculate the zone people count assuming the HVAC system is free-floating using the zone sensible heat balance algorithms. The default people activity level is 130 W. The default sensible heat fraction is 0.6.The default radiant heat fraction is 0.7. Zone Input People Activity Level Schedule Name, Zone Input People Sensible Heat Fraction Schedule Name, and Zone Input People Radiant Heat Fraction Schedule Name are optional. When provided, the default values will be overwritten.

2. When Zone Measured Air Temperature Schedule Name, Zone Input Supply Air Mass Flow Rate Schedule Name, and Zone Input Supply Air Temperature Schedule Name are provided, it will calculate the zone people count assuming the HVAC is on. In this case, the zone air supply air temperature and mass flow rate in the zone sensible heat balance algorithms will be overwritten by the input data.The default people activity level is 130 W. The default sensible heat fraction is 0.6.The default radiant heat fraction is 0.7. Zone Input People Activity Level Schedule Name, Zone Input People Sensible Heat Fraction Schedule Name, and Zone Input People Radiant Heat Fraction Schedule Name are optional. When provided, the default values will be overwritten.

3. When Zone Measured Air Humidity Ratio Schedule Name is provided, it will calculate the zone people count assuming the HVAC system is free-floating using the zone moisture balance algorithms.The default people activity level is 130 W. The default sensible heat fraction is 0.6.The default radiant heat fraction is 0.7. Zone Input People Activity Level Schedule Name, Zone Input People Sensible Heat Fraction Schedule Name, and Zone Input People Radiant Heat Fraction Schedule Name are optional. When provided, the default values will be overwritten.

4. When Zone Measured Air Humidity Ratio Schedule Name, Zone Input Supply Air Mass Flow Rate Schedule Name, and Zone Input Supply Air Humidity Ratio Schedule Name are provided, it will calculate the zone people count assuming the HVAC is on. In this case, the zone air supply air humidity ratio and mass flow rate in the zone moisture balance algorithms will be overwritten by the input data.The default people activity level is 130 W. The default sensible heat fraction is 0.6.The default radiant heat fraction is 0.7. Zone Input People Activity Level Schedule Name, Zone Input People Sensible Heat Fraction Schedule Name, and Zone Input People Radiant Heat Fraction Schedule Name are optional. When provided, the default values will be overwritten.

5. When Zone Measured Air CO$_2$ concentration Schedule Name is provided, it will calculate the zone people count assuming the HVAC system is free-floating using the zone CO$_2$ balance algorithms. The default people activity level is 130 W. The default single person CO$_2$ generation is 0.0000000382 [m$^3$/(s*W)]. Zone Input People Activity Level Schedule Name, Zone Input People CO$_2$ Generation Rate Schedule Name are optional. When provided, the default values will be overwritten.

6. When Zone Measured Air CO$_2$ concentration Schedule Name, Zone Input Supply Air Mass Flow Rate Schedule Name, and Zone Input Supply Air CO$_2$ Concentration Schedule Name are provided, it will calculate the zone people count assuming the HVAC is on. In this case, the zone air supply air CO$_2$ concentration and mass flow rate in the zone CO$_2$ balance algorithms will be overwritten by the input data. The default people activity level is 130 W. The default single person CO$_2$ generation is 0.0000000382 [m$^3$/(s*W)]. Zone Input People Activity Level Schedule Name, Zone Input People CO$_2$ Generation Rate Schedule Name are optional. When provided, the default values will be overwritten.

When YES is selected for Calculate Zone Internal Thermal Mass or Calculate Zone Air Infiltration Rate, this field will be treated as NO.

\paragraph{Field: Zone Measured Air Temperature Schedule Name}\label{field-zone-measured-air-temperature-schedule-name-hm}

This field is the name of the schedule object which contains the zone air temperature measurement data. The date range of the schedule should cover the start and end date of the HybridModel. A Schedule:File object is recommended for inputting the time-series measurements. When a schedule:file object is provided, all the rows for a whole year should be in the file, the rows outside of the start and end date range of the HybridModel should be zeros.

\paragraph{Field: Zone Measured Air Humidity Ratio Schedule Name}\label{field-zone-measured-air-humidity-ratio-schedule-name-hm}

This field is the name of the schedule object which contains the zone air humidity ration measurement data. The date range of the schedule should cover the start and end date of the HybridModel. A Schedule:File object is recommended for inputting the time-series measurements. When a schedule:file object is provided, all the rows for a whole year should be in the file, the rows outside of the start and end date range of the HybridModel should be zeros.

\paragraph{Field: Zone Measured Air CO$_2$ concentration Schedule Name}\label{field-zone-measured-air-co2-concentration-schedule-name-hm}

This field is the name of the schedule object which contains the zone air CO$_2$ concentration measurement data. The date range of the schedule should cover the start and end date of the HybridModel. A Schedule:File object is recommended for inputting the time-series measurements. When a schedule:file object is provided, all the rows for a whole year should be in the file, the rows outside of the start and end date range of the HybridModel should be zeros.

\paragraph{Field: Zone Input People Activity Level Schedule Name}\label{field-zone-input-people-activity-schedule-name-hm}

This field is the name of the schedule referenced by a Schedule object which contains the people activity level data. The date range of the schedule should cover the start and end date of the HybridModel.

\paragraph{Field: Zone Input People Sensible Heat Fraction Schedule Name}\label{field-zone-input-people-sensible-heat-fraction-schedule-name-hm}

This field is the name of the schedule referenced by a Schedule object which contains the people sensible heat fraction data. The date range of the schedule should cover the start and end date of the HybridModel.

\paragraph{Field: Zone Input People Radiant Heat Fraction Schedule Name}\label{field-zone-input-people-radiant-heat-fraction-schedule-name-hm}

This field is the name of the schedule referenced by a Schedule object which contains the radiant heat fraction of the sensible heat data. The date range of the schedule should cover the start and end date of the HybridModel.

\paragraph{Field: Zone Input People CO$_2$ Generation Rate Schedule Name}\label{field-zone-input-people-co2-generation-rate-schedule-name-hm}

This field is the name of the schedule referenced by a Schedule object which contains a single person's CO$_2$ generation rate data. The date range of the schedule should cover the start and end date of the HybridModel.

\paragraph{Field: Zone Input Supply Air Temperature Schedule Name}\label{field-zone-input-supply-air-temperature-schedule-name-hm}

This field is the name of the schedule object which contains the measured supply air temperature data. The date range of the schedule should cover the start and end date of the HybridModel. A Schedule:File object is recommended for inputting the time-series measurements. When a schedule:file object is provided, all the rows for a whole year should be in the file, the rows outside of the start and end date range of the HybridModel should be zeros.

\paragraph{Field: Zone Input Supply Air Mass Flow Rate Schedule Name}\label{field-zone-input-supply-air-mass-flow-rate-schedule-name-hm}

This field is the name of the schedule object which contains the measured supply air mass flow rate data. The date range of the schedule should cover the start and end date of the HybridModel. A Schedule:File object is recommended for inputting the time-series measurements. When a schedule:file object is provided, all the rows for a whole year should be in the file, the rows outside of the start and end date range of the HybridModel should be zeros.

\paragraph{Field: Zone Input Supply Air Humidity Ratio Schedule Name}\label{field-zone-input-supply-air-humidity-ratio-schedule-name-hm}

This field is the name of the schedule object which contains the measured supply air humidity ratio data. The date range of the schedule should cover the start and end date of the HybridModel. A Schedule:File object is recommended for inputting the time-series measurements. When a schedule:file object is provided, all the rows for a whole year should be in the file, the rows outside of the start and end date range of the HybridModel should be zeros.

\paragraph{Field: Zone Input Supply Air CO$_2$ Concentration Schedule Name}\label{field-zone-input-supply-air-co2-concentration-schedule-name-hm}

This field is the name of the schedule object which contains the measured supply air CO$_2$ concentration data. The date range of the schedule should cover the start and end date of the HybridModel. A Schedule:File object is recommended for inputting the time-series measurements. When a schedule:file object is provided, all the rows for a whole year should be in the file, the rows outside of the start and end date range of the HybridModel should be zeros.

\paragraph{Field: Begin Month}\label{field-begin-month-hm}

This numeric field should contain the starting month number (1 = January, 2 = February, etc.) for the period of the measured data during which the hybrid model will be active.

\paragraph{Field: Begin Day of Month}\label{field-begin-day-of-month-hm}

This numeric field should contain the starting day of the starting month (must be valid for month) for the period of the measured data during which the hybrid model will be active.

\paragraph{Field: End Month}\label{field-end-month-hm}

This numeric field should contain the ending month number (1 = January, 2 = February, etc.) for the period of the measured data during which the hybrid model will be active.

\paragraph{Field: End Day of Month}\label{field-end-day-of-month-hm}

This numeric field should contain the ending day of the ending month (must be valid for month) for the period of the measured data during which the hybrid model will be active.

Examples of the object in an IDF are:

\begin{lstlisting}
HybridModel:Zone,
  ZONE 1 HybridModel,         !- Name
  ZONE 1,                     !- Zone Name
  Yes,                        !- Calculate Zone Internal Thermal Mass
  No,                         !- Calculate Zone Air Infiltration Rate
  No,                         !- Calculate Zone People Count
  ,                           !- Zone Measured Air Temperature Schedule Name
  ,                           !- Zone Measured Air Humidity Ratio Schedule Name
  ZONE 1_MeasuredCO2Concentration,  !- Zone Measured Air CO2 Concentration Schedule Name
  ,                           !- Zone Input People Activity Schedule Name
  ,                           !- Zone Input People Sensible Heat Fraction Schedule Name
  ,                           !- Zone Input People Radiant Heat Fraction Schedule Name
  ,                           !- Zone Input People CO2 Generation Rate Schedule Name
  ,                           !- Zone Input Supply Air Temperature Schedule Name
  ,                           !- Zone Input Supply Air Mass Flow Rate Schedule Name
  ,                           !- Zone Input Supply Air Humidity Ratio Schedule Name
  ,                           !- Zone Input Supply Air CO2 Concentration Schedule Name
  1,                          !- Begin Month
  1,                          !- Begin Day of Month
  12,                         !- End Month
  31;                         !- End Day of Month

HybridModel:Zone,
  ZONE 1 HybridModel,         !- Name
  ZONE 1,                     !- Zone Name
  No,                         !- Calculate Zone Internal Thermal Mass
  Yes,                        !- Calculate Zone Air Infiltration Rate
  No,                         !- Calculate Zone People Count
  ,                           !- Zone Measured Air Temperature Schedule Name
  ,                           !- Zone Measured Air Humidity Ratio Schedule Name
  ZONE 1_MeasuredCO2Concentration,  !- Zone Measured Air CO2 Concentration Schedule Name
  ,                           !- Zone Input People Activity Schedule Name
  ,                           !- Zone Input People Sensible Heat Fraction Schedule Name
  ,                           !- Zone Input People Radiant Heat Fraction Schedule Name
  ,                           !- Zone Input People CO2 Generation Rate Schedule Name
  ,                           !- Zone Input Supply Air Temperature Schedule Name
  ,                           !- Zone Input Supply Air Mass Flow Rate Schedule Name
  ,                           !- Zone Input Supply Air Humidity Ratio Schedule Name
  ,                           !- Zone Input Supply Air CO2 Concentration Schedule Name
  1,                          !- Begin Month
  1,                          !- Begin Day of Month
  12,                         !- End Month
  31;                         !- End Day of Month

HybridModel:Zone,
  ZONE 2 HybridModel,         !- Name
  ZONE 2,                     !- Zone Name
  No,                         !- Calculate Zone Internal Thermal Mass
  No,                         !- Calculate Zone Air Infiltration Rate
  Yes,                        !- Calculate Zone People Count
  ,                           !- Zone Measured Air Temperature Schedule Name
  ,                           !- Zone Measured Air Humidity Ratio Schedule Name
  ZONE 2_MeasuredCO2Concentration,  !- Zone Measured Air CO2 Concentration Schedule Name
  OfficeSmall ACTIVITY_SCH,   !- Zone Input People Activity Schedule Name
  People Sensible Heat Fraction Sch,  !- Zone Input People Sensible Heat Fraction Schedule Name
  People Radiation Heat Fraction Sch,  !- Zone Input People Radiant Heat Fraction Schedule Name
  People CO2 Generation Rate Sch,  !- Zone Input People CO2 Generation Rate Schedule Name
  ,                           !- Zone Input Supply Air Temperature Schedule Name
  ZONE 2_Inlet_MassFlow,      !- Zone Input Supply Air Mass Flow Rate Schedule Name
  ,                           !- Zone Input Supply Air Humidity Ratio Schedule Name
  ZONE 2_Inlet_CO2,           !- Zone Input Supply Air CO2 Concentration Schedule Name
  1,                          !- Begin Month
  1,                          !- Begin Day of Month
  12,                         !- End Month
  31;                         !- End Day of Month
\end{lstlisting}


\subsubsection{Outputs}\label{outputs-030}

\begin{lstlisting}
Zone,Average,Zone Infiltration Hybrid Model Air Change Rate [ACH]
Zone,Average,Zone Infiltration Hybrid Model Mass Flow Rate [kg/s]
Zone,Average,Zone Hybrid Model People Count
Zone,Average,Zone Hybrid Model Thermal Mass Multiplier
\end{lstlisting}

\paragraph{Zone Infiltration Hybrid Model Air Change Rate {[}ACH{]}}\label{zone-infiltration-hybrid-model-air-change-rate}

The zone infiltration air change rate calculated by the hybrid model.

\paragraph{Zone Infiltration Hybrid Model Mass Flow Rate {[}kg/s{]}}\label{zone-infiltration-hybrid-model-air-mass-flow-rate}

The zone infiltration air mass flow rate calculated by the hybrid model.

\paragraph{Zone Hybrid Model People Count}\label{zone-infiltration-hybrid-model-people-count}

The zone people count calculated by the hybrid model.

\paragraph{Zone Hybrid Model Thermal Mass Multiplier}\label{zone-infiltration-hybrid-model-thermal-mass-multiplier}

This is the value of the thermal mass multiplier that is the ratio of the zone air heat capacity calculated for current conditions using a heat balance equation to the heat capacity of the volume of air contained in the zone.  This value is 1.0 when one of the following conditions is met: $|T_z^t - T_z^{t-\delta t}| > 0.05^{\circ}C$, the simulation is not currently during the time period for which hybrid modeling is set to run, or the value calculated for this parameter using the above methodology results in a value less than 1.0.  The first time that the value that is calculated for this parameter is greater than 30.0 for a particular zone a warning message is produced in the EnergyPlus Error File (*.err) to inform the user of this occurrence.  A summary of the times for when this parameter is greater than 30.0 for each zone is produced at the end of the standard error file.  Note: when the value does exceed this warning threshold, the value is NOT reset.
